Fix old versions banner on nested pages

docs/change-log.md

@@ -1,4 +1,6 @@
 # Change Log
+## v0.2.6
+- Fix old versions banner on nested pages
 ## v0.2.5
 - Fix docs deploy typo
 ## v0.2.4

docs/javascripts/extra.js

@@ -1,6 +1,6 @@
 window.addEventListener("DOMContentLoaded", function() {
     var xhr = new XMLHttpRequest();
-    xhr.open("GET", window.location + "../versions.json");
+    xhr.open("GET", window.location.origin + "/versions.json");
     xhr.onload = function() {
       var versions = JSON.parse(this.responseText);
       latest_version = ""